What Happens When Women Drop Below 5% Body Fat?

Everybody requires a certain amount of fat to maintain important body functions. Like weight, body fat percentages vary widely based on age and gender, as well as physical conditioning. The bare minimum amount of fat a woman needs to stay healthy ranges between 8 percent and 18 percent, while average body fat percentages for women are between 32 percent and 42 percent. When a woman’s body fat drops below 5 percent, she has lost much of the essential fat needed to maintain her life. She can expect her body to use other sources to fulfill her body’s energy demands. Too little body fat could have anorexic effects and be potentially fatal.

Functions of Fat

Fat has many purposes. It acts as insulation for the body, so having too little body fat can cause problems regulating your body temperature. Women, especially those who starve themselves to low body fat, start growing black hair all over their body to provide some heat. Fat also provides protection and cushion for your organs, so you have a greater likelihood of them being injured with too little body fat. Fat also is a source of stored energy, and you are wired to hold onto some of it. When your stored carbohydrates are depleted, your body has to turn to other sources of energy. Although complex interactions decide which fuel source will be used, your body could turn to protein and start “eating” your muscles to stay powered. It also can tap your skeletal system. These exchanges cause a number of adverse physical consequences.

Menstrual and Fertility Issues

Another role of fat is regulating sex and reproductive hormones. If you have too little body fat, you might produce too little estrogen and begin experiencing irregular periods. They can even stop altogether. Problems with menstruating naturally lead to problems conceiving — and carrying healthy babies. During pregnancy, your body fat requirements grow to support your developing baby. Failing to keep the minimum requirement can cause your child to develop insulin deficiency as he grows. You also might miscarry, and your risk for having a child with birth defects increases.

Bone Fractures

Having too little estrogen as a result of too little body fat can lead to bone fractures, bone thinning and osteoporosis. Decreases in estrogen levels lead to a rapid loss of bone mineral density. The loss of estrogen actually causes cell death in your bone structures.


Fat in your body helps to control inflammation, blood clotting and even brain health. Moreover, many of your organs have some structural fat. This fat is part of the percentage of the essential fat your body needs to stay alive. Without enough, some organs can stop functioning properly.Your risk of premature death begins to rise when your body fat falls below a certain point. As an example, the University of Maryland Medical Center points out that heart disease is the most common cause of death in people with severe anorexia. Although well-conditioned female athletes might have low body fat and not be intentionally starving themselves, a Canadian professor quoted in “Scientific American” says that to achieve such a low level of body fat, unhealthy eating behaviors — even “disordered eating behaviors” — are most likely to occur.